Telegraph repeater



. Jan. 24, 1933. s. VERNAM ET AL 1,895,015

TELEGRAPH REPEATER Filed June 1, 1931 All INVENTORS GILBERT S. VERNAM FREDERICK G. HALLDEN EBY ATTORN Patented Jan. 24, 1933 UN I GILBERT S. VERNABE, OF HAGKENSAOK, NEW JERSEY, AND FREDERICK G. HALLDEN', F BELLEROSE, NEVI YORK, AiSIGNOE-S TO INTERNATIONAL COMMUNICATIONS LABORATORIES, INC., OF 3131 YORK, 11. L, A CORPORATION OF NEW YORK TELEGRAPH REPEATER 'Application filed June 1, 1931.

Our invention relates to improven'ients in impulse repeaters and particularly to repeaters of the type employed in telegraph systems.

The object of our invention is the design of a simple form of repeater which repeats or reproduces the signals transmitted thereto so as to impress stored energy to the line to cause the line current to increase at a much higher rate than it would otherwise. During the transmission of signals the repeater also acts to dissipate the charge potential on the line. Both of these conditions serve to materially improve the efficiency of the repeater.

The repeater consists of two neutral or non-polarized relays which co-operate to produce the foregoing results.

Other features of our invention will be pointed out in the description to follow.

Our invention is illustrated in the accompanying drawing, wherein Fig. 1 shows the repeater circuit and two stations connected thereto, and

Fig. 2 is a modification of the repeater of Fig. 1.

Referring to Fig. 1, the stations 1 and 51 are provided with printing equipment comprising,respectively, print-er magnets 3 and 16 and the keyboards or transmitters 2 and 17.

It should be understood that this printing telegraph equipment is included only to illustrate the operation of the repeater. Any signal transmitting device capable of open ing and closing the circuit might be substituted for the keyboard transmitter, and any device capable of responding to such signals might be substituted for the printer magnet.

Each station is connected to the repeater which comprises two normally energized relays 4 and provided, respectively, with a set of make-before-break contacts 5, 6, 7 and 11, 12, 13.

The repeater in Fig. 2 is also provided with two relays and having, respectively, a set of make-before-break contacts 25, 26, 27 and 31, 32, 33. The relays 20 and 40 are, however, provided with two sets of wind ings instead of with a single winding, as

shown in Fig. 1.

Serial No. 541,254.

he operation of the repeater shown in Fig. 1 is as follows.

The operator at station 1, wishing to signal station 51, operates the keyboard 2 which intermittently opens and closes the line or 5 control circuit extending to the repeater. The opening of the circuit causes a spacing signal to be transmitted, while the closing of the circuit causes a marking signal to be transmitted.

The relay 10 has its circuit normally closed by the following path: ground, battery 19, 15, 10, contacts 6 and 5 of relay 4, 3, 2 to ground.

he opening of the circuit at station 1 causes relay 10 to become de-energized and, in releasing, contacts 12 and 13 are closed before contacts 11 and 12 are broken. The breaking of contacts 11 and 12 disconnects the line circuit extending to station 51 from the winding of relay 4, but the closing of contacts 12 and 13 serves to maintain relay 4 energized over the following local circuit: ground, 19, 9, 4, 12, 13, 14 to ground.

At the opening of the circuit which corresponds to the spacing impulse, the printer magnet 16 at station 51 releases and records the spacing signal.

After the spacing signal is transmitted,

ground is againconnected to the circuit eX- tending from station 1 and causes the relay 10 to be again energized and reconnect the winding of relay 4 to the circuit extending to station 51, thus energizing the magnet 16 and recording the marking signal.

The disconnection and reconnection of the winding with the circuit extending to station 51 continues whlle the slgnals are being transmitted from station 1. At each operation and release of relay 10, all three contacts sistance 14 should preferably be such that the current through the winding of relay 4 is approximately the same when relay 10 is released as when it is energized. If the inductance of printer magnet 16 is comparatively small, so that the line circuit is substantially non-inductive, the current through relay 4 will be nearly constant, except for a small momentary increase when the three contacts 11, 12 and 13 are all engaged. Un-

der these conditions, it is obvious that when contacts 11 and 12 make, the current in the line to station 51 will rise abruptly to its normal steady state value as though relay 4 were a non-inductive resistance. It is also obvious that there will be very little sparking at the contacts of relay 10, as there is no inductive discharge from the winding of relay 4. On the other hand, if magnet 16 has considerable inductance and the line has but little capacity to ground, the current through relay 4 will tend to decrease when contacts 12 and 13 separate, and the decrease in magnetic energy in this relay will induce a potential in the winding in a direction to aid battery 19 in rapidly increasing the line current. This effect can be increased, if desired, by decreasing resistance 14.

The momentary closing of the three contacts as described serves to cause the charge potential in the line circuit to be dissipated and, with the added electromotive force produced by the self-inductance of the relay winding, causes the signals from the output of the repeater to be sharply defined.

The same form of operation occurs when signals are transmittedfrom station 51 to station 1, in which case relay 4 is intermittently operated in response to the signalsv and relay 10 held energized during the transmission of these signals. l

When signals are transmitted from station 1 to the repeater shown in Fig. 2, relay 20 is operated and, upon becoming de-energized, opens at contacts 25 and 26, the circuit extending from battery 39 through winding 30 of relay 40 to the line leading to station 51. Relay 40, however, is held energized through its winding 42 which is connected to battery 39 through contacts 26 and 27.

- As in Fig. 1, the three contacts 25, 26 and 27 are momentarily closed at each operation of relay 20. Instead of applying an enerwinding directly to the line when contacts 25'and 26 are closed, a similar result is produced due to the inductive eflect between the energized winding 42 and winding 30.

This inductive etlect serves to apply to the line an electromotive force in addition to the electromotive force of the battery39. In Fig. 2 as in Fig. 1, signals may be transmitted from station 51 to station 1, in which gized case relay 40 will be intermittently operated and relay 20 held energized during the trans-- mission of these signals.

' battery 19 or 39 associated with the repeater.

If desired, with battery connected to the lines atstations 1 and 51, ground may be substituted for battery 19 or 39. In this case a local battery must be substituted for the grounds shown connected to resistances 8 and 14 or windings 41 and 42, in order to hold each of the relays energized while the corresponding line circuit is open at the contacts of the other relay.

What is claimed is 1. A repeater system comprising two lines, a normally energized relay for each of said lines, each relay provided with a line winding, a local wmding and circuits therefor, each of said lines directly connected to the line winding of its respective relay, a resistance element associated with each of said relays, means associated with each of said lines'tor de-energizing'its respective relay, the de-energizing of one of said relays serving to open the circuit of the line winding of the other relay but maintaining it energized by closure of the circuit through the local winding. and the resistance element associated with the de-energized relay.

2. A re eater system comprising two lines, a normal y energized relay for each of said lines, each relay provided with a line winding, a local winding and circuits therefor, a resistance associate with each of said relays, each of said lines directly connected to the line winding of its respective relay which is normally in series with the resistance associated with the other relay, means associated with each of said lines for de-energizing its respective relay, the de-energization, of one of said relays serving to open the circuit of the line winding of the other relay but maintaining it energized through the circuit of its local winding and the resistance normally in series with its line winding.

3. A repeater system comprising two lines. a normally energized relay for each of said lines, each relay provided with a line winding, a local winding, and circuits therefor, each of said lines line winding of its respective relay, means associated with each of said lines for de-energizing its respective relay, the de-energizing of one of said relays serving to open the circuit of the line winding of the other relay but directly connected to the w but maintaining it energized through the circuit of the local winding and the contacts of the de-energized relay.

5. A. repeater system comprising two lines,

a relay for each of said lines provided with a line winding, a local winding and three contacts only, circuits for each of said windings, each of said relays normally energized by a path including its line winding and its respective line, and contacts of the other relay, means associated with each of said lines for de-energizing its respective relay to operate its contacts, the operating of said contacts serving to open the circuit of the line Winding of the other relay but maintaining it energized through the circuit of the local winding and the contacts of the de-energized relay. In witness whereof we hereunto subscribe out names this 28th day of May, 1931.

GILBERT S. VERNAM. FREDERICK G. HALLDEN. 

